Help with serial comms

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retepsnikrep
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Help with serial comms

Postby retepsnikrep » Tue Mar 10, 2009 1:11 pm

I've been busy lately with analysing the exchange of data betwen the OEM Honda Insight computers and in particlular the BCM Battery Control Module and MCM Motor Control Module.

Now the BCM in my car is virtually redundant so I want to fake it's signals to the MCM and then remove it.

To this end I've been looking at the data being sent between them, but I'm no serial comms experts. So could do with a bit of help.

There is a thread running at IC which has a lot of background info.

http://www.insightcentral.net/forums/mo ... gnals.html

But my latest post is below.

Logic Analyser arrived today. Very neat bit of kit.

Now just need to learn how to use it.

Anyway I captured some data from just before you turn on ignition and then with ignition on for about 5 seconds. Engine not running. The normal signal is on BATTSC1 and an inverted signal on BATTSCI2 ditto the METSCI1 & 2 signals. SOC at 19 bars.

I can share this with other's which is nice you need to install the Logic software from here

http://www.saleae.com/downloads/logi...tup%20Beta.exe

It needs dot.net framework 3.5 as well.

Then you can download my captured data from here, open and fiddle about with it.

http://www.solarvan.co.uk/insight/St...9.logicsession

The data on Input 1 & 2 is the BCM to MCM link BATTSCI1 & 2

This seem to be alternating packets of data in the sample I obtained.

The data on Input 7 & 8 is the BCM to MCM to Dash Display link METSCI1 & 2

This repeats at wider intervals but looks consistent with some small variations.

I'll capture some more later. Please have a look at it and post your thoughts.

Here is a screen capture from the program, this is the first burst of data on the buses after switch on.

Ignore the date in the middle two lines that's a duplicate of the bottom ones. The numbers superimposed are what the program thinks the hex values are for the transmitted data. The shortest pulse is 106us which makes the baud rate? 10,400 poss. But as we don't know the structure, how many data bits, parity, stop, start etc that's still up for discussion.

www.solarvan.co.uk/insight/Data100309.jpg

If you download and install the logic software you can analyse the data with me. All help gratefully recieved.
Regards Peter

Two MK1 Honda Insight's. One running 20ah A123 Lithium pack. One 8ah BetterBattery Nimh pack.
One HCH1 Civic Hybrid running 60ah A123 Lithium pack.

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